Electromagnet



May 14, 1946.

J. F. FRESE 2,400,344 ELECTROMAGNET Filed Sept. 17, 1943 s Sheets-Sheet1 H9 1 Fig 2 I TOR.

May 14, 1946. FREQ; 2,400,344

ELECTROMAGNET Filed Sept, 17, 1943 s Sheets-Sheet 2- IN V EN TOR.

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May 14, 1946. F, FRESE 2,400,344

ELECTROMAGNET Filed Sept. 17, 1943 3 Sheets-Sheet 3 Patented Mai, 1946UNITED STATES PATENT OFFICE ELECTROMAGNET' Joseph F. Frese, Baltimore,Md.

Application September 17, 1943, Serial No. 502,803

(Cl. 175-336) v 3 Claims.

This invention relates to electromagnetically operated switches of thetype wherein the magnet comprises a hollow field piece with themagnetizing coil arranged within the fiield piece. Th inventioncomprises variou features of construction which facilitate theassembling and taking apart of the various parts of the switch and whichincreases its efliciency and it also includes means whereby when twosimilar switches are arranged adjacent one another it is impossible toclose either one of said switches while the other is closed. The detailsof construction of the switch mechanism will be clear from the followingdescription, taken in connection with the accompanying drawings in whichFigure 1 is a front view of two similar electromagnetic switches with aninterlocking device which prevents the closure of either switch whilethe other switch is closed, the magnet coils being shown in dottedlines;

Figure 2 is a side view of the same, looking from left to right inFigure 1;

Figure 3 is a section on the line 33 ofFig- I ure 4;

Figure 4 is a front view, on a'larger scale, of the electromagnet, andmovable contact carrying member shown in the upper part of Figure 1, themagnet coil being shown in dotted lines;

Figure 4* is a side view of one of the contact assemblies, 2. part ofthe contact carrying bar being shown in section on the line .ra: ofFigure 4;

Figure 4 is a plan view of one of the contact members;

Figure 4" is a plan view of one of the metal blanks from which thehousing for the contact and spring is formed;

Figure 5 is a front view of one of the magnet field pieces;

Figure 6 is a perspective view of the hollow coil which fits within thehollow field piece;

Figure '7 is a bottom plan view of the field piece with the shading coiland interlocking guides its supporting links, one of the latter beingshown partly broken away; 4

Figure 13 is a partial section on the line |3-|3 of Figure 12, and

Figure 14 is a side View of the pivot pin which connects the armaturewith the supporting links.

Referring to Figures 1 and 2 of the drawings, A and B represent twosimilar electromagnetic switches arranged one above the othe on a baseplate I which is adapted to stand vertically. The magnets of theswitches are spaced from the base plate by supporting members 3 such asare shown in Frese Patent #2258556, dated October 17, 1941. The lever I,centrally pivoted on a support 4, secured to the base plate, has rollers2 and l at its ends and these are adapted to engage the ends of themovable contact carriers of both switches and prevent the closure ofeither switch while the other switch is closed. The operation of thisinterlocking bar Will be hereinafter described.-

The switches A and B are alike in structure and a description, of oneswitch will apply to the other. Therefore in Figure 4 is shown anelectromagnet with it's armature and the contact carrying member whichit operates in the same positions as the armature and contact carryingmember are shown in switch A, Figure 1, wherein the armature and saidmember are shown in the open position of the switch.

Figure 5 shows the field piece a of the magnet, which is a hollowlaminated structure of rectangular form, having an opening in the centerof its lower wall, forming opposed pole pieces 1), the opening being ofsuiiicien't width to permit the armature guide, hereinafter referred to,to pass through.

Transverse grooves 5 are formed in the bottom wall of the field pieces,adjacent the ends of the pole pieces, and a shading coil 6, shown inFigure 8, has its side portions 6* embedded in these grooves, as shownin Figure 7, while its end portions 6' are bent upwardly and extendacross the gap in the bottom wall of the field piece and spaced a shortdistance from said wall as shown in Figures 4 and 7. Metal guide strapsa, One of which is shown in Figure 9, are secured to the sides of thelower wall of the field piece and these extend across the gap in saidwall, as shown in Figures 1, 4 and 7. Each of the metal guide straps ghas an opening 8 in its central portion, and, opposite this opening, alateral projection 9. These guide straps interlock with the armatureguide pieces, as hereinafter explained. Metal guide straps h, Figures 1,3 and 4, are secured to the opposite sides of the upper wall of thefield piece in alignment with the guide straps a on the lower wall.

In Figure 10 is shown a guide for the armature comprising two identicalcomplementary section 1 and 1', made of thin resilient non-magnetlzable,metal, such as copper or brass, troughlike in cross section, eachsection of the guide having a flat central portion In and parallelsidewalls Ill or equal width, extending at a. right angle to the centralportion, the central portion being slotted longitudinally, forming atongue II, the free end of which is turned slightly outward from theplane oi the central portion, as

shown at H. Each section of the armature.

guide has a flange il extending outwardly at a right angle to the planeof its central portion at the end adlacent the free end of the tongue,and in each flange there is a slot i I' adapted to receive theprojection 9 on one of the metal guide straps a. The ide walls HP ofboth armature guide section are cut off at the ends opposite the flange,forming shoulders I2 and leaving narrow flanges l2 at the margins of thecentral portion extending from said shoulders to the adjacent end of thesection.

The armature k, as shown in Figures 11, 12, and 13, is a one-piecestructure comprising a core l9, rectangular in cross section and a headH at a right angle to the core, the armature being composed o1 T-shapedlaminations. The armature has a transverse bore l'l extending throughthe central part of its head as shown in Figures 11 and 13, and a pivotpin l6, tapering from its center toward both or its ends, extendsthrough this bore. The pivot pin has pintles at its ends which areiournaled in the lower ends or flat metal links, l5, l5- which connectthe armature with the contact-carrying member a when the parts areassembled as shown in Figure 4. Each ture attached are inserted upwardlythrough the armature guide sections and the upper ends the links aresecurely fastened to the contact carrying member by the screws l",Figure 4. The

link is provided with screw holes at its upper end through which screwsl5 may be passed to fasten the upper ends or the links rigidly to thecontact carrying member.

In assembling the parts thus far described, with the field .plece heldin a vertical plane, the coil c (Figure 6) is placed within it and thearmature guide sections 1 and 7" are then passed upwardly through thegap in the lower wall of the field piece within the guide straps g andit until the shoulders l2 engage the upper wall of the field piece whichlimits the upward movement of the guide sections. The guide sectionsextend through the central opening in the coil and hold the coil inplace. As each armature guide section approaches its upward limit ofmovement the end llof its tongue ll enters the slot 8 in the adjacentguide strap a and the projection 9 on said guide strap enters the slotll in the flange ll" 01' the armature guide section. The engagement ofthe tongues of the armature guide sections with the guide straps gprevents accidental displacement of the armature sections and theprojections 9 on the guide straps serve to hold the armatureguidesections in parallel relation.

The short side flanges iron each armature guide section rest against theside oi! the upper wall of the fleld piece where they are retained by aguide strap 11.

After the armature guide sections have been inserted in the fleld piece,as described, the links I! and I! are applied to oppositesides or thearmature, with the ends 01 the conical pivot pin l9 extending into theperforations in the lower ends of the links. Then the links with thearmalinks fit freely within the armature guide and the armature, becauseof its pivotal connection with the links, has a limited rocking movementso that its head can make a fiat contact with the lower wall oi. thefleld piece when the magnet is energized and the armature is drawnupwardly to the position 01 the armature shown in switch B in Figure 1.When the links are within the armature guide sections they lie close tothe flat central positions or said sections, and so long as the linksare in place it is impossible for the tongues l I of the armature guidesections to become unhooked from the slots in the guide straps g, butwhen it is desired to remove the armature guide sections for any reason,such, for instance, as removing the coil, the guide links may beunfastened from the contact carrying member and pulled out oi! thearmature guide, along with the armature, and the tongues on the armatureguide sections can then be pushed inwardly to disengage them from theslots in the guide straps g. The armature guide sections can then bepulled downwardly by taking hold of their flanges II and pressingdownward torelease them from engagement with the projections 9 on theguide straps.

On the contact carrying member a are shown what might be calledcontactassemblages M, each including a housing 1n, open on four sides, eachhousing made from a blank shown in Figure 4 and containing a spring 0and a contact member 11, The spring may be inserted in the housing bycompressing it axially and inserting it through one of the open sides ofthe housing and then turning it to a right angle and releasing it sothat it can expand axially and press the contact piece against the outerend of the housing. Each contact piece has a squared portion n at itscenter which extends through openings in opp site sides of the housing,and the spring normally bears against the central part of the contactpiece and holds it against the outer end of the housing. The contactpiece can be removed by turning it edgewise in the housing and thendrawing it outward through one of the openings.

Stationary contacts 25-29 and 25--29' for the switches are shown only infront view, and not in detail, and the circuits which the switchescontrol are not shown because the switches may be used for variouspurposes. Neither are the circuits for the magnets shown. These circuitscan be closed or opened by switches operated manually or otherwise.Where it is desirable or necessary to have only one switch closed at atime, the interlocking bar I may be provided for preventing thepossibility 01 one switch being closed during the period while the otherswitch is closed. For this purpose the ends of the contact carryingmembers a and b are formed with curved surfaces 20 and 2|, respectively,on their upper sides and the centrally pivoted lev'er has rollers at itsends which engage the corresponding ends of the low field piece havingupper and lower walls, the

lower wall having a gap therein, a magnetizing coil within the fieldpiece, said coil having a central opening, strap guides on the upper andlower walls of the field piece, at each side thereof, each strap guideon the lower wall spanning the gap in said wall and each of the latterguides having an opening therein and a downward projection opposite saidgap, a hollow armature guide com! prising two opposing guide sectionsinsertable through said gap, each guide section having a flange at itslower end, said flange having a slot therein, and having a tongueextending toward said flange, said tongue adapted to interlock with thestrap guide and the projection on thestrap guide adapted to enter theslot in the flange of the armature guide section when the latter isinserted upwardly through the gap in the field piece.

2. An electromagnetic switch mechanism comprising a hollow "field piecehaving upper and lower walls, the lower wall having a gap therein,forming pole pieces at each side of the gap, a magnetizing coil withinthe field piece, said coil having a central opening therethrough, ahollow armature guide within the field piece, in line with said gap andextending through the opening in said coil, said guide comprising twocomplemem tary parts insertable and removable through said gap and eachpart attached to the upper and lower walls of the magnet core, avertically movable member above the magnet field piece, links attachedto said member and extending through said armature guide, and anarmature comprising a core and a head between said links, the head beingpivotally connected to the links below the field piece and the coreextending upwardly between the links.

3. An electromagnetic switch mechanism comprising a hollow field piecehaving upper and lower walls, the lower wall having a gap therein,forming pole pieces at each side of the gap, a magnetizing coil withinthe field piece, said coil having a central opening therethrough, ahollow armature guide within the field piece in line with said gap andextending through the opening in said coil, said guide comprising twocomplementary parts insertable and removable through said gap and eachpart attached to the upper and lower walls of the magnet core, avertically movable member above the magnet field piece, links attachedto said member and extending through said armature guide, an armature,comprising a core and a head, between said links, the head havingacentral transverse bore, a'pivot pin extending through said bore andconnecting the head to the links, said pin tapering from its centralportion toward its ends so as to permit a limited rocking motion of thearmature when the head .is drawn upwardly against the magnet polepieces. v

JOSEPH F. FRESE.

